Hi Allen,

We native speakers will intuitively use the proper word in the proper context, but here are a couple of tips to "reverse-engineer" English thinking.

<em>www.etymonline.com</em> is a good go-to site to look at where our words come from. If you look up each word, you'll see that <em>occur</em> comes from Latin, and is connected with running (just like <em>current</em> and <em>corridor</em>), in the sense of "running to meet".  <em>Happen</em> comes from a norse word meaning chance or luck. There are some archaic expressions such as <em>by hap</em> and <em>good hap</em> which you might come across.  Yes, even the word <em>happy</em> is connected. So, the imagery behind each word is quite different. A good writer will be aware of that.

On top of that, it's useful to remember that words of French/Latin/Greek/etc origin are usually formal in English, whereas the Anglo/Celtic/German/Scandinavian words are the "common langauge". So a formal word in a common context looks out-of-place, or even comical (and vice versa).

Now to your sentences. The first thing is that "a few of lives" is completely incorrect. It also sounds as if the lives were unimportant. The other problems are that "took away" sounds awkward, and "a typhoon which __ last year" is overwritten. A natural sentence would be,

<em>A typhoon last year claimed several lives.</em>

Sorry for leaping between the horns, so to speak. A clearer difference can be seen in these two phrases:

"It just occurred to me" = a thought (no surprise here; formal words are usually abstract ideas)

"It just happened to me" = an event (no surprise either; common words are real and physical)

Hi, Peachey

Very grateful for your detailed interpretation and your interpretation for these two terms "Happen to" and "occurred to" is very useful for me. 

Hi, Alicia

Thanks for you comment as well.

I think "happen" can be used in general things, but "occur" is a formal word, which will be used in news. This is just my thought.